{$F+}
program bisection;
uses crt;
type
  func=function(x:real):real;
function F12(x:real):real;far;
  begin
    F12:=exp(ln(2)*x)+1-x*x*x*x*x;
  end;
function F13(x:real):real;far;
  begin
    F13:=exp(ln(2)*x)+1-(1-x)/3;
  end;
function F23(x:real):real;far;
  begin
    F23:=x*x*x*x*x-(1-x)/3;
  end;
function root(F:func; x,y:real):real;
  const
    eps=0.001;
  var
    mid,fx,fy,fm:real;
  begin
    fx:=f(x);
    fy:=f(y);
{    if fx*fy>0 then halt;
}    repeat
      if abs(fx)<eps then

        begin
          root:=x;
          exit;
        end
      else if abs(fy)<eps then
             begin
               root:=y;
               exit;
             end
                          else begin
                                 mid:=(x+y)/2;
                                 fm:=f(mid);
                                 if fx*fm<=0 then
                                   begin
                                     y:=mid;
                                     fy:=fm;
                                   end
                                             else begin
                                                    x:=mid;
                                                    fx:=fm;
                                                  end;
                                end
    until false;
  end;

function F1(x:real):real;far;
  begin
    F1:=exp(ln(2)*x)+1;
  end;

function F2(x:real):real;far;
  begin
    F2:=x*x*x*x*x;
  end;

function F3(x:real):real;far;
  begin
    F3:=(1-x)/3;
  end;

function accuracy(f:func; a,b:real; var n:integer):real;
  function solution(n:integer):real;
  var
    h,g,sum,x,y:real;
    i:integer;
  begin
    h:=(b-a)/n;
    sum:=0;
    x:=a;
    for i:=1 to n do
       begin
         y:=x;
         x:=x+h;
         G:=f((x+y)/2);
         sum:=sum+G;
       end;
    solution:=sum*h;
  end;
  const
    eps=0.001;
  var
    i1,i2:real;
  begin
    n:=10;
    i1:=solution(n);
    n:=n+n;
    i2:=solution(n);
    while abs(i1-i2)>2*eps do
         begin
           if n>=16383 then break;
           i1:=i2;
           n:=n+n;
           i2:=solution(n);
         end;
    accuracy:=i2;
  end;

var
  a,b,c,I,I1,I2,I3:real;
  n:integer;
begin
  clrscr;
  a:=root(F13,-3,-2);
  b:=root(F12,1,2);
  c:=root(F23,0,1);
  writeln('Point of intersection of graphs');
  writeln('F13=',a:10:10);
  writeln('F12=',b:10:10);
  writeln('F23=',c:10:10);
  writeln;
  I1:=accuracy(F1,a,b,n);
  I2:=accuracy(F2,a,c,n);
  I3:=accuracy(F3,c,b,n);
  I:=I1-I2-I3;
  writeln('Required integral');
  writeln('I:=',I:10:10);
  Readln;
end.